cutlass/include/cute/container/array_aligned.hpp

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#pragma once

#include <cute/config.hpp>

#include <cute/container/alignment.hpp>
#include <cute/numeric/int.hpp>
#include <cute/numeric/math.hpp>

namespace cute
{

template <typename T, std::size_t N, std::size_t Alignment = 16>
struct array_aligned
    : public aligned_struct<Alignment>
{
  /// Make sure the Alignment makes sense wrt the size of elements.
  static_assert(Alignment == 16 || Alignment >= sizeof(T), "Alignment is too small");
  /// Alignment must be a power of two
  static_assert(has_single_bit(Alignment), "Alignment must be a power of two");

  using value_type = T;
  using size_type = std::size_t;
  using difference_type = std::ptrdiff_t;
  using reference = value_type&;
  using const_reference = const value_type&;
  using pointer = value_type*;
  using const_pointer = const value_type*;
  using iterator = pointer;
  using const_iterator = const_pointer;

  CUTE_HOST_DEVICE constexpr
  reference operator[](size_type pos)
  {
    return begin()[pos];
  }

  CUTE_HOST_DEVICE constexpr
  const_reference operator[](size_type pos) const
  {
    return begin()[pos];
  }

  CUTE_HOST_DEVICE constexpr
  reference front()
  {
    return *begin();
  }

  CUTE_HOST_DEVICE constexpr
  const_reference front() const
  {
    return *begin();
  }

  CUTE_HOST_DEVICE constexpr
  reference back()
  {
    // return *rbegin();
    return operator[](N-1);
  }

  CUTE_HOST_DEVICE constexpr
  const_reference back() const
  {
    // return *rbegin();
    return operator[](N-1);
  }

  CUTE_HOST_DEVICE constexpr
  T* data()
  {
    return reinterpret_cast<T*>(storage);
  }

  CUTE_HOST_DEVICE constexpr
  T const* data() const
  {
    return reinterpret_cast<T const*>(storage);
  }

  CUTE_HOST_DEVICE constexpr
  iterator begin()
  {
    return data();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator begin() const
  {
    return data();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator cbegin()
  {
    return begin();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator cbegin() const
  {
    return begin();
  }

  CUTE_HOST_DEVICE constexpr
  iterator end()
  {
    return data() + size();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator end() const
  {
    return data() + size();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator cend()
  {
    return end();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator cend() const
  {
    return end();
  }

  CUTE_HOST_DEVICE constexpr
  bool empty() const
  {
    return size() == 0;
  }

  CUTE_HOST_DEVICE constexpr
  size_type size() const
  {
    return N;
  }

  CUTE_HOST_DEVICE constexpr
  size_type max_size() const
  {
    return size();
  }

  CUTE_HOST_DEVICE constexpr
  void fill(T const& value)
  {
    for (auto& e : *this) {
      e = value;
    }
  }

  CUTE_HOST_DEVICE constexpr
  void clear()
  {
    fill(T(0));
  }

  // Not private, we want trivial type
  //private:

  /// Storage type to use for Elements
  using StorageType = typename uint_byte<static_cast<int>(Alignment)>::type;

  /// Ensure that there's enough storage for all elements
  static_assert(sizeof(StorageType) <= Alignment, "StorageType is too big for given alignment");

  /// Number of elements in the storage
  static constexpr std::size_t storageN = (sizeof(T)*N + sizeof(StorageType) - 1) / sizeof(StorageType);

  /// The storage.
  StorageType storage[storageN > 0 ? storageN : 1];
};

//
// Operators
//

template <typename T, std::size_t N, std::size_t Alignment>
CUTE_HOST_DEVICE constexpr
void clear(array_aligned<T, N, Alignment>& a)
{
  a.clear();
}

template <typename T, std::size_t N, std::size_t Alignment>
CUTE_HOST_DEVICE constexpr
void fill(array_aligned<T, N, Alignment>& a, T const& value)
{
  a.fill(value);
}

} // end namespace cute

//
// Specialize tuple-related functionality for cute::array
//

#include <tuple>

namespace cute
{

template <std::size_t I, class T, std::size_t N>
CUTE_HOST_DEVICE constexpr
T& get(array_aligned<T,N>& a)
{
  static_assert(I < N, "Index out of range");
  return a[I];
}

template <std::size_t I, class T, std::size_t N>
CUTE_HOST_DEVICE constexpr
T const& get(array_aligned<T,N> const& a)
{
  static_assert(I < N, "Index out of range");
  return a[I];
}

template <std::size_t I, class T, std::size_t N>
CUTE_HOST_DEVICE constexpr
T&& get(array_aligned<T,N>&& a)
{
  static_assert(I < N, "Index out of range");
  return std::move(a[I]);
}

} // end namespace cute

namespace std
{

template <class T, std::size_t N>
struct tuple_size<cute::array_aligned<T,N>>
    : std::integral_constant<std::size_t, N>
{};

template <std::size_t I, class T, std::size_t N>
struct tuple_element<I, cute::array_aligned<T,N>>
{
  using type = T;
};

} // end std